<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
  <title>鼠标移入/移出改变样式</title>
  <style>
    body {
      color: lightgreen;
      font: 12px/1.5 Tahoma;
    }

    #div1 {
      width: 150px;
      height: 150px;
      margin: 100px auto;
      padding: 10px;
      background: black;
      border: 10px solid #000;
      cursor: crosshair;
    }

    #div1.hover {
      color: red;
      background: #f0f0f0;
      border: 10px solid red;
    }
  </style>

  <script>
    window.onload = function () {
      var oDiv = document.getElementById("div1");
      oDiv.onmouseover = function () {
        oDiv.className = "hover"
      };
      oDiv.onmouseout = function () {
        oDiv.className = ""
      }
    };
  </script>
</head>

<body>
<div id="div1">鼠标移入改变样式，鼠标移出恢复。</div>
</body>

</html>
